A wireless communication system covers a geographical area which is divided into several radio coverage areas. Such radio coverage areas are often referred to as cells or sectors. Each radio coverage area is served by a radio base station (RBS), which may be denoted in different ways depending e.g. on radio access technology. For example, such RBS may be referred to as eNodeB or eNB for communication systems adapting to Long Term Evolution (LTE) standard. An access point (reception point/transmission point) refers to a set of co-located antennas that provide coverage to one radio coverage area. One RBS may serve one or several such radio coverage areas.
Uplink Coordinated Multi-Point (UL CoMP) is a multi-antenna technique that commonly refers to utilizing received signals from more than one reception point, when performing reception for one communication device. The signals that are received by the various reception points can be combined and processed to obtain a final received signal, whereby also signals low in strength may be received with few errors. This can be compared to the presently more conventional case, where only one reception point, i.e. the serving reception point, is used when performing reception for one communication device.
Uplink performance can be improved quite significantly by using UL CoMP, e.g. in heterogeneous (HetNet) network deployments. Apart of this gain comes from the fact that communication devices in a HetNet deployment that are served by macro RBS reception points but located quite close to a low power RBS reception point (e.g. a pico RBS reception point), can reduce their transmit power with a maintained service quality when using both the macro and pico reception points. Thereby the communication device radiates less interference towards the pico reception point.